On Sun, 9 Aug 2015 09:31:09 GMT, Windmill wrote:

Doesn't the PV panel have a series diode on the output? If a normal Si
diode (not a Schottky) the reverse leakage should be almost
unmeasurable.

It does and the measuring bit is what I can't remember the details of
or the circuit. The LED and it's series resistor might be after the
diode...

But the charging current you'd get from a north-facing window would be
tiny. Did you measure it?

ISTR (badly) a few mA at 0.5 Hz or slower.

If you use something cheap like phone or UTP wire, the 50 metres to s
south window needn't cost much, and you're only looking for a trickle
charge, are you not?

This is true. Cat5 uses 8 * 24 SWG wires. 24 SWG is nearly 0.25 mm^2
so paralleling two pairs gives about 1 mm^2. 1 mm^2 has a resistance
of about 19 mOhms/m so 50 m is about 1 ohm or 2 ohms there and back.
2 ohms and 10 mA is 20 mV, not worth worrying about.

However any route to get south facing is really really tortious. B-(

But I might be able to expose the panel better without quite so much
bother. The panel is KISS compared to time switches, chargers, etc.

--
Cheers
Dave.